Resuscitation device and method

ABSTRACT

A resuscitation device for automatic compression of victim&#39;s chest using a compression belt which exerts force evenly over the entire thoracic cavity. The belt is constricted and relaxed through a motorized spool assembly which repeatedly tightens the belt and relaxes the belt to provide repeated and rapid chest compression. An assembly includes various resuscitation devices including chest compression devices, defibrillation devices, and airway management devices, along with communications devices and senses with initiate communications with emergency medical personnel automatically upon use of the device.

[0001] This application is a continuation of U.S. application Ser. No.09/703,004 filed Oct. 31, 2000, which is a continuation of U.S.application Ser. No. 08/922,723, filed Aug. 27, 1997, now U.S. Pat. No.6,142,962.

FIELD OF THE INVENTIONS

[0002] This invention relates to emergency medical devices and methods.

BACKGROUND OF THE INVENTIONS

[0003] Cardiopulmonary resuscitation (CPR) is a well known and valuablemethod of first aid. CPR is used to resuscitate people who have sufferedfrom cardiac arrest after heart attack, electric shock, chest injury andmany other causes. During cardiac arrest, the heart stops pumping blood,and a person suffering cardiac arrest will soon suffer brain damage fromlack of blood supply to the brain. Thus, CPR requires repetitive chestcompression to squeeze the heart and the thoracic cavity to pump bloodthrough the body. Very often, the victim is not breathing, and mouth tomouth artificial respiration or a bag valve mask is used to supply airto the lungs while the chest compression pumps blood through the body.

[0004] It has been widely noted that CPR and chest compression can savecardiac arrest victims, especially when applied immediately aftercardiac arrest. Chest compression requires that the person providingchest compression repetitively push down on the sternum of the victim at80-100 compressions per minute. CPR and closed chest compression can beused anywhere, wherever the cardiac arrest victim is stricken. In thefield, away from the hospital, it may be accomplished by ill-trainedby-standers or highly trained paramedics and ambulance personnel.

[0005] When a first aid provider performs chest compression well, bloodflow in the body is typically about 25-30% of normal blood flow. This isenough blood flow to prevent brain damage. However, when chestcompression is required for long periods of time, it is difficult if notimpossible to maintain adequate compression of the heart and rib cage.Even experienced paramedics cannot maintain adequate chest compressionfor more than a few minutes. Hightower, et al., Decay In Quality OfChest Compressions Over Time, 26 Ann. Emerg. Med. 300 (September 1995).Thus, long periods of CPR, when required, are not often successful atsustaining or reviving the victim. At the same time, it appears that, ifchest compression could be adequately maintained, cardiac arrest victimscould be sustained for extended periods of time. Occasional reports ofextended CPR efforts (45-90 minutes) have been reported, with thevictims eventually being saved by coronary bypass surgery. See Tovar, etal., Successful Myocardial Revascularization and Neurologic Recovery, 22Texas Heart J. 271 (1995).

[0006] In efforts to provide better blood flow and increase theeffectiveness of bystander resuscitation efforts, modifications of thebasic CPR procedure have been proposed and used. Of primary concern inrelation to the devices and methods set forth below are the variousmechanical devices proposed for use in main operative activity of CPR,namely repetitive compression of the thoracic cavity.

[0007] The device shown in Barkolow, Cardiopulmonary resuscitatorMassager Pad, U.S. Pat. No. 4,570,615 (Feb. 18, 1986), the commerciallyavailable Thumper device, and other such devices, provide continuousautomatic closed chest compression. Barkolow and others provide a pistonwhich is placed over the chest cavity and supported by an arrangement ofbeams. The piston is placed over the sternum of a patient and set torepeatedly push downward on the chest under pneumatic power. The victimmust first be installed into the device, and the height and strokelength of the piston must be adjusted for the patient before use,leading to delay in chest compression. Other analogous devices providefor hand operated piston action on the sternum. Everette, ExternalCardiac Compression Device, U.S. Pat. No. 5,257,619 (Nov. 2, 1993), forexample, provides a simple chest pad mounted on a pivoting arm supportedover a patient, which can be used to compress the chest by pushing downin the pivoting arm. These devices are not clinically more successfulthan manual chest compression. See Taylor, et al., External CardiacCompression, A Randomized Comparison of Mechanical and ManualTechniques, 240 JAMA 644 (August 1978). Other devices for mechanicalcompression of the chest provide a compressing piston which is securedin place over the sternum via vests or straps around the chest.Woudenberg, Cardiopulmonary Resuscitator, U.S. Pat. No. 4,664,098 (May12, 1987) shows such a device which is powered with an air cylinder.Waide, et al., External Cardiac Massage Device, U.S. Pat. No. 5,399,148(Mar. 21, 1995) shows another such device which is manually operated. Inanother variation of such devices, a vest or belt designed for placementaround the chest is provided with pneumatic bladders which are filled toexert compressive forces on the chest. Scarberry, Apparatus forApplication of Pressure to a Human Body, U.S. Pat. No. 5,222,478 (Jun.29, 1993) and Halperin, Cardiopulmonary Resuscitation and AssistedCirculation System, U.S. Pat. No. 4,928,674 (May 29, 1990) show examplesof such devices.

[0008] Several operating parameters must be met in a successfulresuscitation device. Chest compression must be accomplished vigorouslyif it is to be effective. Very little of the effort exerted in chestcompression actually compresses the heart and large arteries of thethorax and most of the effort goes into deforming the chest and ribcage. The force needed to provide effective chest compression createsrisk of other injuries. It is well known that placement of the handsover the sternum is required to avoid puncture of the heart during CPR.Numerous other injuries have been caused by chest compression. See Jonesand Fletter, Complications After Cardiopulmonary Resuscitation, 12 AM.J. Emerg. Med. 687 (November 1994), which indicates that lacerations ofthe heart, coronary arteries, aortic aneurysm and rupture, fracturedribs, lung herniation, stomach and liver lacerations have been caused byCPR. Thus the risk of injury attendant to chest compression is high, andclearly may reduce the chances of survival of the victim vis-à-vis aresuscitation technique that could avoid those injuries. Chestcompression will be completely ineffective for very large or obesecardiac arrest victims because the chest cannot be compressed enough tocause blood flow. Chest compression via pneumatic devices is hampered inits application to females due to the lack of provision for protectingthe breasts from injury and applying compressive force to deformation ofthe thoracic cavity rather than the breasts.

[0009] CPR and chest compression should be initiated as quickly aspossible after cardiac arrest to maximize its effectiveness and avoidneurologic damage due to lack of blood flow to the brain. Hypoxia setsin about two minutes after cardiac arrest, and brain damage is likelyafter about four minutes without blood flow to the brain, and theseverity of neurologic defect increases rapidly with time. A delay oftwo or three minutes significantly lowers the chance of survival andincreases the probability and severity of brain damage. However, CPR andACLS are unlikely to be provided within this time frame. Response tocardiac arrest is generally considered to occur in four phases,including action by Bystander CPR, Basic Life Support, Advanced LifeSupport, and the Emergency Room. By-stander CPR occurs, if at all,within the first few minutes after cardiac arrest. Basic Life Support isprovided by First Responders who arrive on scene about 4-6 minutes afterbeing dispatched to the scene. First responders include ambulancepersonnel, emergency medical technicians, firemen and police. They aregenerally capable of providing CPR but cannot provide drugs orintravascular access, defibrillation or intubation. Advanced LifeSupport is provided by paramedics or nurse practitioners who generallyfollow the first responders and arrive about 8-15 minutes afterdispatch. ACLS is provided by paramedics, nurse practitioners oremergency medical doctors who are generally capable of providing CPR,drug therapy including intravenous drug delivery, defibrillation andintubation. The ACLS providers may work with a victim for twenty tothirty minutes on scene before transporting the victim to a nearbyhospital. Though defibrillation and drug therapy is often successful inreviving and sustaining the victim, CPR is often ineffective even whenperformed by well trained first responders and ALS personnel becausechest compression becomes ineffective when the providers becomefatigued. Thus, the initiation of CPR before arrival of first respondersis critical to successful life support. Moreover, the assistance of amechanical chest compression device during the Basic Life Support andAdvanced Life Support stages is needed to maintain the effectiveness ofCPR.

SUMMARY

[0010] The devices described below provide for circumferential chestcompression with a device which is compact, portable or transportable,self-powered with a small power source, and easy to use by by-standerswith little or no training. Additional features may also be provided inthe device to take advantage of the power source and the structuralsupport board contemplated for a commercial embodiment of the device.

[0011] In its simplest form, the device includes a broad belt whichwraps around the chest and is buckled in the front of the cardiac arrestvictim. The belt is repeatedly tightened around the chest to cause thechest compression necessary for CPR. The buckles and/or front portion ofthe belt are anatomically accommodating for the female breast, or forthe obese person, so that the device is effective for women as well asmen. The buckle may include an interlock which must be activated byproper attachment before the device will activate, thus preventingfutile belt cycles. The operating mechanism for repeatedly tighteningthe belt is provided in a support board, and comprises a rollingmechanism which takes up the intermediate length of the belt to causeconstriction around the chest. The roller is powered by a small electricmotor, and the motor powered by batteries and/or standard electricalpower supplies such as 120V household electrical sockets or 12V DCautomobile power sockets (car cigarette lighter sockets). (An initialprototype used a power drill with a single 9.6V rechargeable battery,and provided powerful chest compression for about ten minutes.) Thebatteries and any necessary transformers may be housed in the supportboard, and the support board may be made in sizes useful for supportingthe victim's head, adequate for storing batteries and other accessories,and convenient for mounting within office buildings, factories,airplanes and other areas of potential need. Thus, numerous inventionsare incorporated into the portable resuscitation device described below.

[0012] The portable resuscitation device may incorporate a number offeatures and accessories that aid in the administration of CPR and othertherapy. By-standers may be unable to confidently determine if chestcompression is needed, or when it should be stopped. Accordingly, thedevice may be combined with an interlock system including a heartmonitor or EKG which diagnoses the condition of the patient, andcircuitry or a computer which initiates, permits or forbids beltoperation accordingly. The power supply provided for belt constrictionmay also be used to provide power for defibrillation (an appropriatetreatment for many cardiac arrests). Again, bystanders will most likelynot be capable of determining when defibrillation is appropriate, andthe defibrillation portion of the device may be provided with aninterlock system including the heart monitor or EKG which diagnoses thecondition of the patient and circuitry which initiates, permits, orforbids defibrillation. Expert systems implemented through the circuitryor computer modules can accomplish these functions.

[0013] Automatic, computer driven therapy of this nature may provideearly and appropriate life saving response to many cardiac arrestpatients who would otherwise die. However, some situations in which thedevice might be used may call for expert supervision of the CPR processby emergency medical technicians, emergency room doctors, orcardiologists. To this end, the expert systems mentioned above may bereplaced with the expert diagnosis and decision-making of medicalpersonnel through a telemetry system housed within the support board ofthe device. The support board can include a telemetry system whichautomatically dials medical personnel in a nearby hospital, emergencymedical crew, ambulance, or even a central diagnostic and controlfacility. Interlocks, limit switches and other typical sensors can beused to sense the proper position and closure of the belt about thechest of the patient. Heart monitors and EKG electrodes can sense theheart rate and EKG of the victim. Using communication equipment withinthe device, this information can be communicated from the device tomedical personnel remote from the victim. Through the same system, themedical personnel can communicate the device to initiate, permit orprohibit belt constriction or defibrillation, as dictated by preferredmedical procedures. Communication can be established through normaltelephone lines and a cordless telephone, or through a cellulartelephone system, paging system, internet or any other communicationssystem. The device can be programmed with location information, orprovided with GPS capabilities to determine the location of the device,and this information can be automatically transmitted to an emergencyresponse system such as the 911 system when the system is placed in use.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]FIG. 1 is an overview of the resuscitation device, showing theinner and outer vests partially open.

[0015]FIG. 2 is an overview of the resuscitation device in the buckledconfiguration.

[0016]FIG. 3 is an detail view of the buckle used to close the deviceabout a victim.

[0017]FIG. 4 shows the spool assembly used to operate the compressionbelt.

[0018]FIG. 5 shows an alternative embodiment of the spool assembly usedto operate the compression belt.

[0019]FIG. 6 is a view of the resuscitation device properly positionedon a victim.

[0020]FIG. 7 shows the resuscitation device fitted with a number ofadditional devices for use during resuscitation.

[0021]FIG. 8 shows a detail view of the CRP module of FIG. 7.

[0022]FIG. 9 shows a detail view of the defibrillation module of FIG. 7.

[0023]FIG. 10 shows a detail view of the airway management module ofFIG. 7.

[0024]FIG. 11 shows a detail view of the control and communicationsmodule of FIG. 7.

[0025]FIG. 12 shows a block diagram of the communications system.

[0026]FIG. 13 is a block diagram of the motor control system.

DETAILED DESCRIPTION OF THE INVENTIONS

[0027]FIG. 1 shows a simplified version of the resuscitation device 1.The mechanisms used for compressing the chest includes compressionassembly 2 which includes a chest compression belt 3 with buckles 4L and4R, a friction liner 5, a support board 6 and a motor driven spoolassembly 7. The support board 6 is placed under a cardiac arrest victim,and the compression belt 3 and friction liner 5 are wrapped around thevictim's chest. The chest compression belt, having a left side 3L and aright side 3R, is buckled over the victims chest by latching the buckles4L and 4R together. In this configuration, the friction liner 5 will fitbetween the chest compression belt 3 and the victim and any clothes wornby the victim. The compression belt may be made of any strong material,and sail cloth has proven adequate for use. The compression belt mayalso be referred to as a vest, corset, girdle, strap or band. Thefriction liner may be made of Teflon®, Tyvek™ or any other low frictionmaterial (by low friction, we mean a material that will permit slidingof the compression belt with less friction than expected between thebelt and the victims clothing or bare skin). The friction liner may bemade with any suitable lining material, as its purpose is to protect thevictim from rubbing injury caused by the compression belt, and it mayalso serve to limit frictional forces impeding the compression beltoperation. The friction liner can be provided in the form of a belt,vest, corset, girdle, strap or band, and may partially or completelyencircle the chest.

[0028] The front of the compression belt 3, including the buckles 4L and4R, are configured to provide a broad pressure point over the sternum ofthe victim. This is illustrated in FIG. 2. Large openings 8 may beprovided to accommodate female breasts and obese male breasts. Theunderside of the buckles 4L and 4R are smooth and broad, to distributecompressive force evenly over a wide area of the chest corresponding tothe sternum. The point at which the buckle attaches to the chestcompression belt may vary considerably, from the front of the chest tothe back of the compression assembly, and the openings 8 may be providedin the buckles rather than the belt itself. FIG. 3 shows a detail of thebuckles 4L and 4R used to fasten the compression belt about the chest ofthe victim. The buckle may be of any type, and preferably includes alatch sensing switch 9 operably connected through wire 10 to the motorcontrol system (see FIG. 13) to indicate that the device has beenbuckled about the victim's chest and is ready for the initiation ofcompression cycles. The buckles shown in FIG. 3 are D-ring shapedbuckles with large openings 8, attached to the compression belt 3. Otherfasteners and fastening means may be used.

[0029] The chest compression belt 3 is repeatedly tightened about thechest of a victim through the action of one or more tightening spoolswhich make up the spool assembly 7 located within the support board 6.The spool assembly, illustrated in FIG. 4, includes at least one spoolor reel connected to the compression belt 3 at the back of the belt,preferably near the center or saggital line 11 of the compression belt(although it may be located on the front or side of compression belt).FIG. 4 shows a view of the spool assembly and its attachment to thecompression belt. A spool assembly includes a single drive spool 12operably connected to the motor 14 through drive shaft 15. Thecompression belt is secured to the drive spool in any suitable manner.In this case a longitudinal slot 16 provided in the drive spool 12. Theslot extends radially or chordally through the drive spool, and extendsaxially for a length corresponding to the width of the compression belt,leaving the ends 17 solid for connection to the drive shaft 15 andjournal shaft 18. The belt is slipped through the slot to created asecure connection between the belt and the drive spool. When secured inthis manner, the rotation of the drive spool 12 will take up the rightside of the compression belt 3R and the left side of the compressionbelt 3L and roll them up onto the spool, thus tightening the compressionbelt about the chest of the victim wearing the device. Spindles oralignment rollers 19 provide for alignment and low friction feed of thebelt onto the roll created by operation of the drive shaft.

[0030] Many alternative embodiments can be envisioned for the rollingmechanism, and one such alternative is illustrated in FIG. 5. Spools 12Land 12R are aligned in parallel and interconnected by a transmissiongear 20 and planetary gear 21 and journaled upon shafts 18L and 18R. Thedrive shaft 15 is attached to spool 12R (or spool 12L) and operablyattached to motor 14. The motor turns the shaft 18R and spool 12R in acounterclockwise direction to pull the right side of the compressionbelt 3R to the left and roll onto the spool. The transmission gear 20acts upon the planetary gear 21 to cause clockwise rotation of spool12L, which in turn pulls and wraps the left side of the compression belt3L onto the spool 12L.

[0031] Thus, many embodiments of mechanisms which can cause repeatedcyclic tightening of the compression vest about the chest of the victimmay be envisioned. The compression belt serves to radially compress thechest through the cooperative action of the belt, board, and buckle, andto disperse the compressive force around the chest.

[0032] The motor is energized to rotate the spools and cause thecompression belt to constrict around the chest of a victim. A motor suchas a battery operated hand drill motor provides adequate chestcompression for the purposes of CPR. To cause repetitive constriction ofthe compression belt 3, the motor 14 must be attached via a clutch 22 orother such mechanism. The motor 14 may be attached to the drive shaft 15through a torque slipping clutching mechanism which engages the driveshaft until a high torque is achieved (indicating great resistance tofurther constriction, and thus indicating that the victim's chest hasbeen compressed), and releases automatically upon such high torque, onlyto re-engage after the belt has been expanded in response to the normalelastic expansion of the victim's chest. In this manner, repetitivecompression is achieved without need to repeatedly energize andde-energize the motor, thereby extending the length of operating timefor any given battery supply. Alternatively, the motor may be repeatedlyenergized and de-energized, with the spools spinning freely duringperiods in which the belt is de-energized, wherein the clutch mechanism22 will be similar to clutch mechanisms used on electric drills (whichengage during operation of the drill but spin freely when the drill isde-energized). While the natural elastic expansion of the chest shouldmake it unnecessary to drive the belt toward a loose condition, positiveloosening may be achieved by reversing the motor or reversing the actionof the motor through appropriate clutch or gear mechanisms. Timing ofcompressions is regulated through a computer module or a simple relay(windshield wiper style relays), and preferably will conform to standardof the Advanced Cardiac Life Support guidelines or CardiopulmonaryResuscitation guidelines, or any other medically acceptableresuscitation regime. Current guidelines put forth by the American HeartAssociation call for 60-100 chest compressions per minute.

[0033] The motor is preferably battery powered, with provisions fortaking power from any available power source. Batteries 23 may be storedwithin the support board 6. Three volt batteries of convenient size,already available for use with numerous power tools, provide about fiveminutes of compression per battery, while twelve volt batteries (1700mA-h per battery) have provided about ten minutes of compression perbattery. A thirty minute total battery capacity is desirable(corresponding to the estimated average time between cardiac arrest andtransport to the hospital). Accordingly, several batteries may beinstalled within the support board and electrically connected to themotor and its controller. The batteries are provided with a tricklecharge through a charger socket and charger plugged into 120V AC powerwhen the device is not in use. (It is intended that the device beinstalled in factories, office buildings, airplanes and other facilitieswith relatively stable sources of power, and that the unit remainplugged in and charging when not in use.) If AC power is readilyavailable at the site of use, the device may continue to run on AC powerto preserve the batteries for later use. The unit may also be pluggedinto an automobile power jack with an appropriate auto adapter, thusproviding for use where an automobile is the only source of power, andfor extended use in an ambulance.

[0034]FIG. 6 shows the resuscitation device installed on a cardiacarrest victim. The support board is placed under the victim, and theright and left portions of the compression belt are wrapped around thevictim's chest and buckled over the front of the chest, indicated byarrow 25. Once in place, the system may be put into operation bymanually starting the motors or by automatic initiation given the properfeedback from sensors located on the device, including the buckle latchsensors.

[0035] A number of features may be combined with the basic systemdescribed above. The structure necessary for housing the operatingmechanism for the belt, referred to as the support board above, canserve also as storage for additional devices used during resuscitation.FIG. 7 illustrates the resuscitation device 1 in a potential commercialembodiment. The support board 6 is sized to reach approximately from thelower lumbar region to the shoulders of a victim. The compression module26 is separable from the support board 6, and includes the compressionbelt and friction vest stored within the compression module. The spoolassembly and motor are also stored within the compression module,although the motor may also be installed in the support board. In thisfigure, the compression module comprises a small support board 27 whichfits into the larger system support board 28. Taking advantage ofavailable space in the system support board, a compartment 29 forstorage of airway management devices (bag masks, oxygen masks, etc.),and a compartment 30 for storage of defibrillation equipment (electrodesand paddles, etc.) are included with the support board. A control andcommunication module 31 may also be incorporated into the support board.A small oxygen bottle 32 may be included, along with hoses routed to anaccessible point on the board, and any connector desired for connectionbetween the oxygen bottle and devices provided in the airway managementcompartment. Batteries 23 are stored within the support board (thenumber of the batteries chosen according the desired operating time, andthe placement of the batteries dictated by available space). Batteriesare operably connected to the motor in the compression module throughelectrical connectors 33 and appropriate wiring throughout the supportboard. The batteries can also be operably connected to thedefibrillation module and control and communications module. Althoughlong life batteries can be used, rechargeable batteries may bepreferred. Accordingly, charging connection 34 on the support board isprovided for charging the batteries or operating the device throughoutside power supplies.

[0036] The device is intended to be stored for long periods of timebetween uses, and storage holder 35 is provide for this purpose. Thestorage holder can include such necessities as power supply connectors,power plug, a charging transformer. A removal sensor 36 is included inthe support board to sense when the support board is removed from thestorage holder (which, as described below, can be used as a conditionindicating use of the device, and therefore the need to alert emergencymedical personnel). The removal sensor can comprise a simple limitswitch which senses physical removal of the system, and the limit switchcan be used as a power switch or awaken switch which starts initiationof the system. The removal sensor can comprise a current sensor on thecharging lines which treat cessation of charging current, increase incurrent draw through the charging system, or motor current as anindication of use. The choice of sensor may be made with many practicalconsiderations in mind, such as the desire to avoid treating poweroutages as indications of use and other such unintended initiations. Thestate in which the device is deemed to be “in use” can be chosenaccording to the practical considerations, and in most instances it isexpected that mere removal of the resuscitation device from the holderwill constitute a clear signal someone has determined that a victimrequires its use, and that emergency medical personnel should bedispatched to the location of the device. There are some environments inwhich later conditions will be used to indicate that the device is “inuse,” such as when installed in ambulances, airplanes, hospitals orother environments where it might be advisable to remove the device fromits storage holder as a precaution or preparatory measure, and delayinitiation of communications until the device is deployed or installedon the victim. In such cases, the buckle latch shown in FIG. 3 can beused as the sensor that indicates that the resuscitation device is inuse.

[0037]FIG. 8 shows the details of the compression module 26. When not inuse, the module is covered with a tear sheet 37 which protects thecompression belt from wear. The buckles are readily visible under thetear sheet. The electrical connectors 38 connect the batteries in thesupport board with the motor inside the compression module. The insideof the compression belt is fitted with penetrating electrodes 39 in theright sternum parasaggital location 40 and left rib medial location 41for establishing the electrode contact needed for EKG sensing. Theseelectrodes may be dispensed in environments where proper placement ofthe defibrillation electrodes can be assumed due to a high level oftraining amongst likely bystanders and first responders. The frictionvest 5 is secured to the compression module above the spool assemblylocation.

[0038]FIG. 9 shows a detail view of the defibrillation module in thecompartment 30. The defibrillation module includes a pair ofdefibrillation electrodes 42 connected to the batteries through thepower connections 43. The defibrillation electrodes will be controlledby circuitry housed within the defibrillation module, and may beconnected to the control module through the data port 44. Thedefibrillation module is releasably attached to the support board 28with quick release latches 45. Tear sheet 46 protects the components ofthe defibrillation module during storage and provides ready access foruse. FIG. 10 shows the detail view of the airway management module inthe compartment 29, which includes an oxygen mask 47, a length of tubing48 and an air fitting 49 connecting the oxygen mask to the oxygen bottlewithin the support board. The oxygen mask serves as a blood gas exchangemeans, supplying oxygen to the lungs for exchange with blood gas such asCO₂. Optional medicine injectors 50 may be operably connected to themasks or hose to provide for automatic injection of ACLS medicationsinto the airway. The defibrillation module is releasably attached to thesupport board 28 with quick release latches 51. Tear sheet 46 protectsthe components of the airway management module during storage andprovides ready access for use. An end-tidal CO₂ monitor 52 can beincluded in the mask to provide for biological feedback and monitoringof the success of the CPR. A skin mounted blood oxygen level monitor 53can also be mounted on the mask for the same purpose (fingertip bloodoxygen sensors may also be used, and supplied in the overall assembly tobe readily available). The biological data obtained by the sensors istransmitted to the control module via appropriate wiring in the mask andsupport board.

[0039]FIG. 11 shows a detail view of the control and communicationsmodule. The control unit 54 is connected to the compression module,defibrillation module and the airway management module throughappropriate wiring through the support board. The control unit isoptionally connected to the communications unit 55. The communicationsunit includes means for communicating the EKG and other measured medicalparameters sensed on the board to the screen 56 and via telephone toremote medical personnel. The communications unit can include atelephone handset or speaker phone. Because the device is most likely tobe used at a location separate from the storage holder, thecommunications module preferably includes a wireless communicationdevice, such as wireless telephone, radio telephone or cellular, and anynecessary telephone base will be installed in the storage holder.

[0040] The communications unit and control unit are set up to operate inthe following manner, also illustrated in the block diagram of FIG. 12.The device may remain mounted in a charging unit for months between use,and will be removed from the charging unit for use. Upon removal of thedevice from its storage location, a sensor in the control unit sensesthe removal (through limit switches, magnetic switches, or motionsensors, current sensors in the charging system, or otherwise) andinitiates the system, checking functions, energizing a display unit andaccomplishing other typical warm-up functions. As a first step, thesystem initiates a telephone communication with a medical facilitythrough the communications unit. The communication may use anycommunication medium, whether it be standard telephone lines, cellulartelephone system, paging system or radio transmitter. The system may beset up to initiate communications with central medical facility, such asa local 911 emergency system, a nearby hospital or ambulance service, ora central facility staffed with medical personnel trained specificallyon the remote use of the device (all generally referred to as medicalpersonnel). Upon establishing communication, the communications unitinforms medical personnel of the location or identification of thedevice (which may be stored in computer memory in the communicationsunit, or determined through GPS or other such system), and thisinformation can be used to dispatch an emergency medical team to thelocation of the device. In a simple embodiment which does not require acomputer to control the actions of the alert feature, the removal sensormay comprise a limit switch, while the communications module maycomprise a simple telephone unit installed in the storage holdertogether with a tape recorded message, where the operation of the relayin response to removal of the resuscitation device includes initiationof the telephone call to 911 and playback of an alert message providingalert information such as the location of the board. The communicationsunit may also be provided with an alert button which may be operated bya bystander regardless of the use of the board to summon an emergencyteam to the location regardless of the condition of the resuscitationdevice.

[0041] Before the emergency medical team arrives, a bystander will placethe board under the victim, buckle the compression belt around thevictim and apply defibrillation and/or sensing electrodes (or viceversa)(alternatively, sensing electrodes can be included on the innersurface of the compression belt). The system monitors the installationof the belt through signals provided through latching sensors in thebuckle. The system monitors biological input, which can comprisemonitoring of EKG signals from the EKG electrode patches of thedefibrillation module, monitoring EKG signals belt mounted electrodes,monitoring signals from an end-tidal CO₂ monitor from the airwaymanagement module, and any other biological signal sensor incorporatedinto the device. The system can also monitor or respond to manuallyinputted instruction from the control unit, in order to provide on-siteemergency medical personnel with control of the device when they arriveon scene. During operation, the system transmits all availablebiological information, including EKG signals, blood pressure, end-tidalCO₂ and any other monitored biological parameter to the remote medicalfacility, and it can also transmit information regarding theconfiguration of the device, including battery life, system operatinglimit settings (i.e., whether the system is set for automatic operation,permissive operation, or disabled in any function) so that medicalpersonnel can ensure that the appropriate configuration is in effect.

[0042] Communication with the medical facility will allow emergencymedical personnel to diagnose the condition of the patient and, throughsignals sent from the medical personnel to the communications unit,permit, initiate or prohibit certain additional therapeutic ACLSactions. For example, upon diagnosing the EKG conditions which indicatethe need for defibrillation, the medical personnel can send a signal tothe communications unit which acts upon the control unit to permitmanual operation of the defibrillation electrodes by the bystander. Thesystem also provides for application of a defibrillation shock viaremote signal from the medical personnel. The device can incorporate theexpert system such as the Automatic External Defibrillator. The medicalpersonnel can also communicate other actions, and ensure that certainacts are undertaken by the bystander through the communication system.For example, the medical personnel may communicate verbally with thebystander to ascertain the cause of the cardiac arrest, the properplacement of the oxygen mask, appropriate clearing of the airway, andother information. Where the airway management module is provided withmedication such as epinephrine, lidocaine, bretylium or other drugscalled for in the ACLS guidelines (or newly proposed drugs such as T3),the medical personnel can instruct by-standers to inject appropriatemedication through the airway. Where automatic injectors such as thosedescribed in Kramer, Interactive External Defibrillation and DrugInjection System, U.S. Pat. No. 5,405,362 (Apr. 11, 1995) are provided,or similar system with non-osseous injectors are provided, the medicalpersonnel can instruct by-standers to inject appropriate medicationthrough these injectors. Where the injectors are provided with means forautomatic operation based on measured EKG signals, blood pressure andend-tidal CO₂, the medical personnel can send signals to the system toinitiate injection by remote control of the medical personnel, permitinjection by local control as determined by the expert system, permitinjection by by-standers, or prohibit injection by the system orbystanders. For example, the system can be initially set up to forbidany injection. Medical personnel, having diagnosed ventricularfibrillation through the information provided by the communicationsunit, can send an appropriate signal to permit or initiate injection ofepinephrine, and also send a signal to prohibit injection of atropineuntil called for under the ACLS guidelines. A newly proposed drug T3 canbe administered through the airway, into the lungs, as a therapy forcardiac arrest. Controlled injection into the airway can be initiated orprohibited in the same manner. Thus, all actions in the ACLS, includingcompression, defibrillation, drug injection can be accomplished throughthe system under the guidance of medical personnel from a remotelocation, or they may be accomplished through expert systems installedin the control module. Each of these functions in incorporated in asystem that automatically initiates communication with medical personneland informs medical personnel of the location of the device so thatemergency medical personnel my be dispatched to the location.

[0043] The repeated compression will be initiated upon buckling of thecompression belt (automatically) or a switch can be provided for thebystander to initiate compression. The system will continue compressioncycles, until de-activated, according the motor control block diagram ofFIG. 13. Upon initiation of the system, the control unit will monitorinstallation of the belt via appropriate sensors in the buckles orthrough other sensors. When the motor control 57 receives the initiatecompression signal from the control unit, the motor is started. Themotor is preferably run continuously, rather than stopped and started,to avoid repeated application of startup current and thus conservebattery power. When the motor is up to speed, the clutch is engaged. Asa baseline, the clutch is engaged every second for one-half second. Thiscyclic engagement of the clutch continues repeatedly for five cycles, asrecommended by current CPR guidelines, and then is interrupted for arespiration pause, if desired. To avoid excessive drain on thebatteries, the motor controller includes a torque sensor (sensingcurrent supply to the motor, for example), and monitors the torque orload on the motor. A threshold is established above which furthercompression is not desired or useful, and if this occurs during the halfsecond of clutch engagement, then the clutch is disengaged and the cyclecontinues. The system can monitor the effectiveness of the compressionstroke by monitoring the CO₂ content of the victim's exhalant. Where CO₂content is low, indicating inadequate circulation, the control systemincreases the torque limit until the CO₂ levels are acceptable (or untilthe maximum torque of the motor is achieved.) This is another example ofthe device's use of biological signals to control operation of thesystem. The cycle time and period, number of cycles between respirationpauses, and the torque limit, can be set according to currentguidelines, and can also be varied by the remote medical personnel viathe remote control capabilities of the control unit.

[0044] Thus, while the preferred embodiments of the devices and methodshave been described in reference to the environment in which they weredeveloped, they are merely illustrative of the principles of theinventions. Other embodiments and configurations may be devised withoutdeparting from the spirit of the inventions and the scope of theappended claims.

We claim:
 1. A method of performing chest compressions on a patient incardiac arrest, said method comprising the steps of: providing a chestcompression device comprising: chest compression means for compressingthe chest of the patient; a controller for operating chest compressionmeans, said controller being operable to operate the chest compressionmeans to compress the chest to variable thresholds; and a biologicalparameter sensor for sensing a biological parameter of the patient andtransmitting a signal corresponding to the sensed biological parameterto the controller; wherein the controller is programmed to adjust thevariable threshold of the chest compression means based upon the signalcorresponding to the sensed biological parameter; applying the chestcompression means to the chest of the patient; operating the chestcompression means to compress the chest of the patient; and while thepatient is in cardiac arrest and the device is in operation compressingthe patient's chest to a degree sufficient to perform CPR, adjusting thevariable threshold of the chest compression based on the sensedbiological parameter.
 2. The method of claim 1 wherein the biologicalparameter sensor is an end-tidal CO₂ sensor which senses CO₂ in thehuman's exhalant and which transmits a signal corresponding to the levelof CO₂ in the exhalant to the controller, and the controller adjusts thevariable threshold of chest compression based on the sensed end-tidalCO₂.
 3. The method of claim 1 wherein the biological parameter sensor isa blood oxygen sensor which senses the level of oxygen in the patient'sblood and which transmits a signal corresponding to the level of oxygenin the patient's blood to the controller, and the controller adjusts thevariable threshold of chest compression based on the level of oxygen inthe patient's blood.
 4. The method of claim 1 wherein chest compressiondevice is motor driven, and the controller controls the operation of themotor to limit torque applied by the motor to a variable torque limit toeffect a desired amount of compression, wherein the torque limit and thedesired amount of compression are based upon the signal corresponding tothe sensed biological parameter.
 5. The method of claim 4 wherein thecontroller operates the motor to achieve chest compressions, and limitsoperation of the motor to a predetermined load threshold, and thecontroller further adjusts the load threshold based upon the sensedbiological parameter.
 6. The method of claim 5 wherein the controllerincreases the load threshold if the sensed biological parameterindicates that inadequate circulation has been achieved by the chestcompression device.
 7. The method of claim 1 wherein the step ofproviding a chest compression device further comprises providing asource of drugs, providing a means for automatically injecting drugsinto the patient, operably connecting the source of drugs to the meansfor automatically injecting drugs, operably connecting the means forautomatically injecting drugs to the controller, programming thecontroller to operate the means for automatically injecting drugs basedon a sensed biological parameter and operably connecting the means forautomatically injecting drugs to the patient.
 8. A method of performingchest compressions on a patient in cardiac arrest, said methodcomprising the steps of: providing a chest compression devicecomprising: a belt adapted to extend at least partially around the chestof a human; a rotating member operatively connected to the belt toconstrict the belt around the chest; a motor for rotating the rotatingmember; a controller for operating the motor and thereby operating therotating member; and a sensor for sensing a biological parameter of thehuman and transmitting a signal to the controller, wherein thecontroller is programmed to control operation of the motor based uponthe signal corresponding to the sensed biological parameter; wrappingthe belt at least partially around the chest of the patient; operatingthe device to compress the chest of the patient; and while the patientis in cardiac arrest and the device is in operation compressing thepatient's chest to a degree sufficient to perform CPR, controllingoperation of the motor based on the sensed biological parameter.
 9. Themethod of claim 8 wherein step of providing a device further comprisesproviding an end-tidal CO₂ sensor which senses CO₂ in the human'sexhalant and which transmits a signal corresponding to the level of CO₂in the exhalant to the controller.
 10. The method of claim 8 wherein thestep of providing a device further comprises providing a blood oxygenlevel sensor which senses the level of blood oxygen in the human's bloodand which transmits a signal corresponding to the level of blood oxygento the controller.
 11. The method of claim 8 wherein the controllercontrols the operation of the motor to limit torque applied by the motorto a variable torque limit to effect a desired amount of compression,wherein the torque limit and the desired amount of compression are basedupon the signal corresponding to the sensed biological parameter. 12.The method of claim 8 wherein the controller operates the chestcompression device to achieve variable degrees of compression based uponthe sensed biological parameter.
 13. The method of claim 8 wherein thecontroller operates the motor to cause the belt to compress the chest tovarying degrees of compression, and further operates the motor toachieve differing degrees of compression based upon the sensedbiological parameter.
 14. The method of claim 8 wherein the controlleroperates the motor to achieve chest compressions, and limits operationof the motor to a predetermined load threshold, and the controllerfurther adjusts the load threshold based upon the sensed biologicalparameter.
 15. The method of claim 14 wherein the controller increasesthe load threshold if the sensed biological parameter indicates thatinadequate circulation has been achieved by the chest compressiondevice.
 16. The method of claim 15 wherein the step of providing adevice further comprises providing an end-tidal CO₂ sensor.
 17. Themethod of claim 15 wherein the step of providing a device furthercomprises providing a blood oxygen level sensor.
 18. The method of claim8 wherein the step of providing a device further comprises providing asensor selected from the group consisting of an end-tidal CO₂ sensor, ablood oxygen level sensor, an ECG sensor and a blood pressure sensor.19. The method of claim 8 wherein the step of providing a device furthercomprises providing a defibrillator.
 20. The method of claim 19 whereinthe step of providing a device further comprises operably connecting thedefibrillator to the controller, programming the controller to operatethe defibrillator based on a second sensed biological parameter andoperably connecting the defibrillator to the patient.
 21. The method ofclaim 8 wherein the step of providing a device further comprisesproviding a source of drugs and a means for injecting the drugs into thepatient.
 22. The method of claim 21 wherein the step of providing adevice further comprises providing a means for automatically injectingthe drugs into the patient, operably connecting the means forautomatically injecting drugs to the controller, programming thecontroller to operate the means for automatically injecting drugs basedon a second sensed biological parameter and operably connecting themeans for automatically injecting drugs to the patient.